Weight Gain After Lung Volume Reduction Surgery Is Not Correlated With Improvement in Pulmonary Mechanics: Results

25 Sep
2014

To examine whether the weight gain occurred in the patients who were most nutritionally depleted, we compared the percentage of change in body weight with the baseline BMI. In general, there was a trend toward higher percentage increases in weight in patients who had lower baseline BMIs, but this did not reach statistical significance (Fig 3).
Weight Gain After LVRS Is Greater in Women
We compared the weight gain 1 year after LVRS in men and women. Women gained significantly more weight than the men (9.2 vs 2.2%, respectively; p < 0.005, unpaired t test; Fig 4). There were no differences between men and women in baseline BMI (see Table 1) or pulmonary function (FVC, FEV1, RV, TLC, RV/TLC, or Dlco; data not shown). Thus, the weight gain after LVRS is more prominent in women than in men.
Correlation Between Weight Gain After LVRS and Change in Pulmonary Function
We sought to determine if the gain in weight correlated with changes in pulmonary function. Table 2 summarizes weight, BMI, and pulmonary function at baseline and at the 12-month follow-up evaluation in the 38 patients seen 12 months after LVRS. There were statistically significant improvements in FEV1, FVC, and Dlco, and declines in RV, TLC, and RV/TLC ratio. These changes are comparable to previous reports of pulmonary function improvement after bilateral LVRS.- To determine if improvement in pulmonary function was correlated with weight gain 12 months after LVRS, we performed a simple linear regression of the percentage change in individual parameters of lung function and percentage change in body weight. There was no correlation found between percentage change in weight and percentage change in FEV1, FVC, RV, TLC, or RV/TLC (data not shown). However, there was a significant positive correlation between change in weight and change in Dlco (Fig 5). Reading here

Figure 3. Correlation between body weight change 1 year after LVRS and baseline BMI; p = 0.16, simple regression.

Figure 3. Correlation between body weight change 1 year after LVRS and baseline BMI; p = 0.16, simple regression.

Figure 4. Effect of LVRS on body weight change in men vs women, showing significantly greater weight gain in women (p < 0.005, unpaired t test). Data expressed as body weight change (% ± SEM) at 1 year.

Figure 4. Effect of LVRS on body weight change in men vs women, showing significantly greater weight gain in women (p < 0.005, unpaired t test). Data expressed as body weight change (% ± SEM) at 1 year.

Figure 5. Correlation between change in body weight and change in Dlco 1 year after LVRS; p < 0.02, simple regression.

Figure 5. Correlation between change in body weight and change in Dlco 1 year after LVRS; p < 0.02, simple regression.

Table 2—Baseline and Postoperative Characteristics in Patients 1 yr After LVRS

CharacteristicsNo. of Patients EvaluatedPreoperative(Baseline)Postoperative (12 mo)Change
Weight, kg3867.7 ± 2.470.6 ± 2.4t3.9
BMI, kg/m23823.6 ± 0.725.0 ± 0.7t1.4
FVC, % pred3865.4 ± 2.8 16.1
FEVj, % pred3826.0 ± 1.2 10.1
RV, % pred35294.7 ± 11.4 -77.9
TLC, % pred35146.7 ± 3.3133.1 ± 3.2-13.6
RV/TLC, %3565.5 ± 1.4 -11.4
Dlco, % pred3544.9 ± 2.049.7 ± 2.3t4.8
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